Create title screens

Before the talk recordings and after them we need to display the sponsor logos from Platinum - Bronze sponsors. This is separate from the video sponsor loop that is used during breaks (cf. #5 (closed)).

We need 3 screens:

1. Opening
2. Apology (used when something went wrong)
3. Closing

Examples from previous years:

1. DC20: Opening, Apology, Closing
2. DC19: Opening, Closing
3. DC18: Opening, Closing
4. DC17: Opening, Closing